1. Field of the Invention
The present invention generally relates to safety door mechanisms and more particularly to such safety door mechanisms for use in combination with dispensing machines. Through the use of a unique linkage mechanism, access to the interior of a dispensing machine and the products therein contained is prevented upon the opening of access to the dispensing chamber of the machine.
2. Description of the Prior Art
Dispensing machines have typically utilized a dispensing chamber into which the product to be vended is delivered. The product is retrieved from the dispensing chamber by the purchaser, usually through a delivery door. Devices utilizing such an arrangment require that the dispensing chamber be in communication with the product storage area located within the machine through a product supply chute so that the item to be vended can be delivered to the dispensing chamber. Obtaining access to the dispensing chamber has also resulted in obtaining access to the product storage area. Upon obtaining access to the dispensing chamber, the product storage area can be reached through the product supply chute. This structure has created the possibility of a person obtaining items from the product storage area for which he has not yet paid.
Dispensing machines of the prior art utilize various devices to solve this problem. Typically, such devices have employed a supply door to close-off the product supply chute upon opening of the delivery door. In one such device, the supply doors are normally open to permit passage of an item from the product storage area into the dispensing chamber and are operatively connected to the delivery door in a manner such that movement of the delivery door in an opening direction closes the supply door. Another such device utilizes a supply door which is normally maintained in a closed position. A sensing device within the product supply chute opens the normally closed supply door upon passage of an item from the product storage area. Such devices usually are quite complex, and are susceptible to low realiability.
The prior art devices, however, have all proven to be unsatisfactory for one reason or another. Those devices utilizing a normally open supply door are operatively connected to the delivery door in such a manner that when the delivery door is partially opened, the supply door is only partially closed. While such devices may have proved satisfactory to prevent the passage of a human hand from the dispensing chamber into the product supply chute, they do not completely eliminate access to the product storage area. Various tools can be utilized by vandals to obtain access to product storage area through such partially closed supply doors. With such devices, problems have also been encountered by animals such as rodents and the like which can obtain access to the product storage area through a partially open delivery door and a partially closed supply door, which combination may otherwise be a sufficient guard against access by human hands. Those devices utilizing the normally closed supply door have generally proven to be unsatisfactory due to the complicated machinery required for their implementation.